Bees provision most of the pollen removed from anthers to their larvae and transport only a small proportion to stigmas, which can negatively affect plant fitness. Though most bee species collect pollen from multiple plant species, we know little about how the efficiency of bees\' pollen transport varies among host plant species or how it relates to other aspects of generalist bee foraging behavior that benefit plant fitness, such as specialization on individual foraging bouts.
We compared the pollen collected and transported by three bee species for 46 co-occurring plant species. Specifically, we compared the relative abundance of pollen taxa in the individual bees\' scopae, structures where bees store pollen to provision larvae, with the relative abundance of pollen taxa on the rest of bees\' bodies, which is more likely to be transferred to stigmas.
Bees carried five times more pollen grains in their scopae than elsewhere on their bodies. Within foraging bouts, bees were relatively specialized in their pollen collection, but transported proportionally less pollen for the host plants on which they specialized. Across foraging bouts, two bee species transported proportionally less pollen for some of their host plants than for others, though differences didn\'t consistently follow the same trend as at the foraging bout scale.
Our results suggest that foraging-bout specialization, which is known to reduce heterospecific pollen transfer, also results in less-efficient pollen transport. Thus, bee foragers that visit predominantly one plant species may have contrasting effects on that plant\'s fitness.

So far, oil-rewarding flowers are known to be pollinated only by oil-collecting bees, which gather and use lipids for larval feed and nest building. As honeybees do not have oil-collecting appendages on their legs, they have not been associated with pollination of such flowers. In a predominantly Apis pollinated and food deceptive clade of wild Cymbidiums, we investigated the reproductive strategy of Cymbidium aloifolium, hitherto unknown for its floral oil reward. Our study demonstrates the requisites for establishment of mutualistic interaction between the oil flower and Apis cerana indica, a corbiculate bee. Success in pollination requires learning by honeybees to access the food reward, thereby displaying cognitive ability of the pollinator to access the customized reward. Morphometric matching between orchid flowers and the pollinator, and that between pollinia and stigmatic cavity also appear to be essential in the pollination success. Absence of pollinator competition and prolonged flower-handling time are suggested to promote floral constancy. The present study highlights the need to explore the spectrum of pollination rewards pursued by honeybees, which may include unconventional composition of floral resources.

Individual pollinators that specialize on one plant species within a foraging bout transfer more conspecific and less heterospecific pollen, positively affecting plant reproduction. However, we know much less about pollinator specialization at the scale of a foraging bout compared to specialization by pollinator species. In this study, we measured the diversity of pollen carried by individual bees foraging in forest plant communities in the mid-Atlantic United States. We found that individuals frequently carried low-diversity pollen loads, suggesting that specialization at the scale of the foraging bout is common. Individuals of solitary bee species carried higher diversity pollen loads than did individuals of social bee species; the latter have been better studied with respect to foraging bout specialization, but account for a small minority of the world\'s bee species. Bee body size was positively correlated with pollen load diversity, and individuals of polylectic (but not oligolectic) species carried increasingly diverse pollen loads as the season progressed, likely reflecting an increase in the diversity of flowers in bloom. Furthermore, the seasonal increase in pollen load diversity was stronger for bees visiting trees and shrubs than for bees visiting herbaceous plants. Overall, our results showed that both plant and pollinator species\' traits as well as community-level patterns of flowering phenology are likely to be important determinants of individual-level interactions in plant-pollinator communities.

Learning facilitates behavioral plasticity, leading to higher success rates when foraging. However, memory is of decreasing value with changes brought about by moving to novel resource locations or activity at different times of the day. These premises suggest a foraging model with location- and time-linked memory. Thus, each problem is novel, and selection should favor a maximum likelihood approach to achieve energy maximization results. Alternatively, information is potentially always applicable. This premise suggests a different foraging model, one where initial decisions should be based on previous learning regardless of the foraging site or time. Under this second model, no problem is considered novel, and selection should favor a Bayesian or pseudo-Bayesian approach to achieve energy maximization results. We tested these two models by offering honey bees a learning situation at one location in the morning, where nectar rewards differed between flower colors, and examined their behavior at a second location in the afternoon where rewards did not differ between flower colors. Both blue-yellow and blue-white dimorphic flower patches were used. Information learned in the morning was clearly used in the afternoon at a new foraging site. Memory was not location-time restricted in terms of use when visiting either flower color dimorphism.

•
OBJECTIVE: Ultraviolet (UV) floral patterns are common in angiosperms and mediate pollinator attraction, efficiency, and constancy. UV patterns may vary within species, yet are cryptic to human observers. Thus, few studies have explicitly described the distribution or ecological significance of intraspecific variation in UV floral patterning. Here, we describe the geographic distribution and pattern of inheritance of a UV polymorphism in the model plant species Mimulus guttatus (Phrymaceae). We then test whether naturally occurring UV phenotypes influence pollinator interactions within M. guttatus.•
METHODS: We document UV patterns in 18 annual and 19 perennial populations and test whether UV pattern is associated with life history. To examine the pattern of inheritance, we conducted crosses within and between UV phenotypes. Finally, we tested whether bee pollinators discriminate among naturally occurring UV phenotypes in two settings: wild bee communities and captive Bombus impatiens.•
RESULTS: Within M. guttatus, perennial populations exhibit a small bulls-eye pattern, whereas a bilaterally symmetric runway pattern occurs mainly in annual populations. Inheritance of UV patterning is consistent with a single-locus Mendelian model in which the runway phenotype is dominant. Bee pollinators discriminate against unfamiliar UV patterns in both natural and controlled settings.•
CONCLUSIONS: We describe a widespread UV polymorphism associated with life history divergence within Mimulus guttatus. UV pattern influences pollinator visitation and should be considered when estimating reproductive barriers between life history ecotypes. This work develops a new system to investigate the ecology and evolution of UV floral patterning in a species with extensive genomic resources.